Motor-compressor unit for refrigerating apparatus



NOV. 24, 1936. I HORLACHER 2,062,052

MOTOR COMPRESSOR UNIT FORREFRIGERATING APPARA TUS Filed June 30, 1932 Patented Nov. 7 1936 PATENT cur os aosaosz MOTOR-COMPRESSOR UNIT FOR BEFRIGEBATING APPARATUS Elmer L. Horlacher, Dayton, Ohio, assignor, by

memo assignments, to General Motors Corporation, a corporation of Delaware Application June 30, 1932, Serial No. 620,195

6 Claims. (01. sac-2i) This invention relates to refrigerating apparatus and more particularly to unloading means for motor-compressor units.

In order to facilitate starting, it is common to provide motor compressor units with unloadin means.

An object of my invention is to provide a motor-compressor unit having an unloading chamber, a by-pass, and a single electro-magnet -valve means which closes the entrance to the unloading chamber and opens a by-pass with a single movement w en the compressor stops, and which, with a s e movement, opens the entrance to the unloading chamber and closes the by-pass when the compressor starts or reaches a predetermined speed range. r

Another object of my invention is tdprovide a motor-compressor unit havingan electro-magnetic unloading means controlled by a separate exciting winding in the electric motor.

Further objects and advantages of the present invention will be apparent from the following description,'reference being had to the accompanying drawing, wherein a preferred form of the present invention is clearly shown.

In the drawing:

Fig. 1 is a diagrammatic illustration'of one form of my invention showing a sealed electric motor compressor unit together with the remaining elements of a refrigeration system; and d Fig. 2 is a sectional view of the motor compressor unit showing my electro-magnetic unloading means.

Referring to the drawing and more particularly to Fig. 1, there is shown diagrammatically a sealed motor compressor unit 20 containing an electric motor 2[ having a rotor 22. The motor preferably is provided with the usual running winding 23 and starting winding 24. A winding inductively excited by the rotation of the motor is provided for actuating an unloading mechanism, and this winding preferably may be in the form of a separate exciting winding 25. The starting and running windings 2t and 23, as well as the separate exciting winding 25 are all suitably wound in the stator portion of the motor 2!. The separate exciting winding is in inductive relation with the rotor and the starting and running windings. By reason of this inductive relation, electric energy is generated when the motor operates. It is to be understood, however, that if desired, the separate exciting winding may be made separate from the motor proper and in inductive relation to separate means rotated by the motor for generating electrical energy within the separate exciting winding. The rotor 22 is preferably directly connected to a compressor 23, shown diagrammatically, where the refrigerant is compressed and forwarded through the conduit 21 to a condenser 28 where the refrigerant is liquefied and collected in the receiver 29. From the receiver 29 the liquid refrigerant is forwarded through a supply conduit 30'to an evaporator 3| of the float controlled. type which controls the admission of liquid refrigerant in accordance with the level of liquid refrigerant within the evaporator. The liquid refrigerant within1the evaporator 3| vaporizes because of the absorption of heat and is returned to the, compressor through the return conduit 32. The operation of the motor compressor unit is controlled by a, snap acting low pressure switch 33 which is connected to the re- [starting winding circuit when the motor 2| reaches a certain predetermined speed. This starting relay 36 is energized by current from the separate exciting winding 25. The separate exciting winding 25 has electric energy generated therein during the operation of the electric motor which varies in voltage with thespeed of the motor, but ordinarily not in a direct relation thereto. The starting relay is so adjusted that when the proper voltage is generated by the separate exciting winding 25 at the predetermined desired tripping speed of the motor, the starting relay 36 will open the starting winding circuit and cause'the starting winding thereafter to be ineffective.

In order to facilitate the starting of the motor compressor unit and to reduce the amount of starting torque required, I provide an improved unloading means for the compressor. One of the elements of this unloading means is an unloading chamber 40 to which the return conduit 32 is connected. The unloading chamber Ml is also connected to the compressor by the inlet passage 4|. A by-pass 42 connects the unloading chamber with the discharge side of the compressor. Within theunloading chamber 40 there is provided an electro-magnetic valve means 43 which, when de-energized, is adapted to closethe entrance to 2 i pressor will fill the unloading chamber 49 during idle periods of the compressor so that the pressure upon the intake and discharge side of the I compressor will be equalized. 1

The electro-magnetic valve means 43 is con-. nected by electrical conductors 44 and 45 to the separate exciting winding 25. After the compressor starts the gas will be pumped from the unloading chamber 43 to the discharge side of the compressor but since the by-pass 42 is open, the

pressure will remain the same on both sides of the compressor and only suflicient work will be done by the electric motor to overcome the fric-.

loading chamber49 and from the return or suction conduit 32 as has been customary.

The construction of the motor-compressor unit together. with the electro-magnet unloading means is shown in Fig. '2. In Fig. 2 there is shown a housing 59 which is generally cylindrical v in shape but having a thick web 58 across the top thereof. Fastened to the top of the housing 59 by means of cap screws 52 is a top cover 53 which is sealed by means of a suitable lead gasket 54. At the bottom of the housing59 there is provided a bottom plate 55 which is also fastened to the housing by means of cap screws 56 and sealed by means of a suitable lead gasket 5'1. The bottom plate is provided with an upstanding boss 58 containing a bearing 59 which supports the lower end of a vertical rotor shaft 89.

Mounted upon the rotor shaft 69 is a rotor M of the squirrel cage type which is surrounded by a stator 62 which is mounted upon and within the walls of the housing 59 by the long. screws 64.

The stator 62 has wound thereon the running,

starting and the separate exciting winding designated in general by the reference character 68. At the upper side of the rotor GI there is provided a bearing 66 which is fixed within the web 5| of the housing 59. The bearing 86 supports the upper end of the rotor shaft 69. The upper end of the rotor shaft 59 is provided with an eccentric portion 61 upon which is fitted a ball bearing 88. -,Upon the outer portion of the ball bearing. 88, there is fitted a disk-shaped gyrator 89 which has an annular ring '59 depending from its lower surface which fits into an annular groove H in the web 5i ofthe housing 59. A suction passage 72 leads vaporized refrigerant to the outer side of the annular groove 7 i. The passage I3 through the ring 19 of the gyrator 69 is provided to feed the refrigerant to the space in the annular groove H on inner side of the ring I9.

As the motor rotates the oscillating ring 19 draws.

vaporized refrigerant into the annular groove H and carries and compresses the refrigerant around the groove to the discharge ports 14 and 15 which are provided with check valves I9 and H of the flapper valve type. The inlet passages 12' and 13 are separated from the discharge ports.

lects upon the bottom plate'55. The bottom poraoeaooa tion or the rotor shaft an is provided with a spiral groove 93 which feeds the lubricant during the operation of the compressor to a drilled passage 94 within the rotor shaft 69. The drilled passage 94 conducts lubricant tothe top of the rotor shaft 69 and from this point the lubricant flows over the gyrator 69 and over the ball bearing 68 to provide adequate lubrication for the compressor. An upper spiral groove 95 connects with the drilled passage 94 to provide lubrication for the upper bearing 66.

-Within the housing 59, at one side thereof, there is provided an unloading chamber 89. At the bottom, of the unloading chamber 89 there is a plug 8| which has an entry passage 82 adapted to be connected to the return conduit 92. The suction passage 12 connects to the upper portion of the unloading chamber 89. Within the unloading chamber 89 there is provided a valve plate 83. A by-pass 84 extends from the interior of the housing 59 to the valve plate. 83. A valve seat 85 is provided in the valve plate 93 at the entrance of this by-pass 84 into the unloading chamber 89..

Within the unloading chamber 89 there isprovided an electro-magnetic valve means comprising a double-ended valve 86 having a needle valve 81 at its lower end for closing the entrance 82 of the unloading chamber 89 and having at its uppr end a needle'valve 88 which is yieldingly mounted by means of a spring 88. A pin and slot means 89 controls the amount of movement permitted between the upper needle valve 87 and themain portion 86. of the double-ended'valve. The double-ended valve 86 is preferablymade of a suitable magnetic material such as soft iron. Surrounding the double-ended valve 86 there is provided an electro-magnetic coil 99. When the coil 99 is not energized, the valve 86 falls by gravity, and the needle valve 81 at its lower end closes the entrance 82 to the unloading chamber 89 while the needle valve' 81 at its upper end uncovers the by-pass 84. This permits the high pressure gas in the interior of the housing 59 to flow into the unloading chamber 89 and equalize the pressure upon both sides of the compressor. When the motor starts and attains sufficient speed, the separate exciting coilwill supply sumcient electrical energy and at a proper voltage to as to lift the valve to close the by-pass 84 at the proper time and toopen the entrance 82 to the unloading chamber 89. A disc 9! of soft iron is provided on the double-ended valve 88 in order to increase the effectiveness of the electro-magnet- 99. In this way, the starting of the motor compressor unit is facilitated but after the motor acquires sufiicient speed, the motor compressor unit will operate under full load. 9 x

While'I disclose as a preferred embodiment, a

motor-compressor unit of the sealed unit type having a gyrator ring compressor, it is to be understood that such an illustration is merely for the purpose of illustrating my invention, and that my invention is applicable to other types of motor-compressor, units, such as the ordinary reciprocating type as well. The starting relay 86 and the electro-magnetic valve means 53 are shown connected inparallel to the separate exciting winding 25, but, if desired, these may be connected in series with the separate exciting winding 25. I! desired, the electro-magnet unloadingvalve may be energized by current in 9,062,052 either the main or the starting winding of the electric motor 28.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. An intermittently operating motor compressor unit including a compressor and a single phase induction type electric motor for driving the compressor, said electric motor having a stator with a starting and running winding wound thereon, an unloading means for said compressor, and a third winding separated from the starting and running windings but wound therewith upon the stator, said third winding being inductively excited by the windings of the motor for controlling said unloading means.

2. An intermittently operating motor-compressor unit including a compressor driven by a single phase induction type electric motor, a starting relay for said electric motor, an electromagnetic unloading means for said compressor, and a winding inductively excited by the windings of the motor and in which the voltage increases with the speed for supplying electric energy to said starting relay and said electromagnetic unloading means.

3. An intermittently operating motor-compressor unit including a compressor having an intake and a discharge portion and an induction type electric motor for driving the compressor, a valve for closing the intake portion of the compressor, and electromagnetic means for opening said valve when said motor-compressor unit attains a certain speed including a separate winding inductively excited by the windings of the electric motor.

4. An intermittently operating motor-compressor having an intake portion with a capacity chamber connected thereto and a discharge portion, said capacity chamber having an inlet, an induction type electric motor for driving the compressor, an inlet valve for closing the inlet to the capacity chamber, a by-pass between the capacity chamber and the discharge portion, a bypass, vaive for closing said by-pass, and electromagnetic means for opening said inlet valve and closing the by-pass valve when the motor attains a certain speed including a separate winding inductively excited by the windings of the electric motor.

5. An intermittently operating motor-compressor unit including a compressor driven by a single phase induction type electric motor, an unloading means for said compressor, and a winding separate from the windings of the motor but inductively excited by the, windings of the motor in which the voltage increases with the speed for controlling said unloading means.

6. An intermittently operating motor compressor unit including a compressor and a single phase induction type electric motor for driving the compressor, said electric motor having a stator with a running and a starting winding wound thereon, a by-pass connecting the intake and discharge sides of said compressor, an electromagnetic valve means capable of closing said by-pass, and a third winding wound upon said stator but separate from the running winding inductively excited by the windings of the motor for operating said electromagnetic valve means.

, ELMER L. HORLACHER. 

